


Undertale: The Six Souls

by emiko_nya



Category: Undertale (Video Game)
Genre: Gen
Language: English
Status: In-Progress
Published: 2019-10-23
Updated: 2019-11-02
Packaged: 2020-12-31 20:15:31
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 4,248
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21151577
Author URL: https://archiveofourown.org/users/emiko_nya/pseuds/emiko_nya
Summary: I don't know what I'm doingAlphys asks Frisk to help her with something, and thus the butterfly effect begins.





	1. Chapter 1

“Ah, there you are, Frisk,” Toriel says as I enter the house.  
I take a glance at the clock in the corner of the room. It says 7 o’ clock; I must have been out longer than I thought.  
“Hey, Toriel,” I reply, after flopping myself down onto an armchair with a relaxed sigh.  
“Alphys was looking for you.”  
That changes my mood completely. What does Alphys want? I feel a sense both of curiosity and of dread.  
“Alphys, huh? Why?” I ask.  
“She didn’t elaborate much; she just said it was for an experiment, and it uses your Determination.”  
I smile wryly. "No offense to her, but the last experiment she did with Determination didn't go that well…" I think back to the strange, melted Amalgamates, and shiver. There's no way I'm gonna let myself become that.  
"Don't worry so much, Frisk. You're human, you can handle lots of Determination." Toriel sounds uncertain, but she’s doing her best to assure me that everything will go smoothly.  
“That doesn’t really help, but okay. I’ll head to the lab now.”  
I stand up, and depart from home with a quick goodbye to Toriel.

Once I arrive, I knock at the metal door. There’s no reply, even after a couple of minutes, so I rap at the door a second time, with more force. Another minute passes, then it finally opens. Alphys appears in front of me, looking rather flustered. “O—oh, Frisk! I didn’t think you’d show up so s—soon!”  
Inside the lab, I hear the sound of a fish crashing through a window, and chuckle to myself quietly.  
“A—anyway, come on in. We have a lot of stuff t—to do.”  
I follow her through the entrance to the main room, full of various machines, half of which are most likely only there for cosmetic reasons. Alphys takes a set at a desk and invites me to do the same. I look around for a chair, but I can’t one, so I just sit on a nearby table.  
“Okay,” she says. “Th—thank you for coming. I have an important question to a—ask you.”  
I nod. “Go on.”  
“S—so, remember when the barrier broke?”  
I give a grunt of confirmation.  
“Nobody else remembers what happened… b—but, you do, right?”  
“Yes...” I think I know where this is going.  
“So, can you t—tell me… what did happen?”  
I lean back, bracing myself to deliver a long speech. “That’s a long story. So. You know Asriel, the dead prince?”

“...and then he said that I should be leaving, not trying to talk to him at that leaf pile. So I came back to you guys, and, well, you know the rest.”  
Alphys scribbles that last part down onto her notepad, then looks back up at me. “Amazing… to think one of th—the experiments I thought failed ended up b—breaking the barrier…”  
“Well, he also nearly killed me several times. But yeah, you’re right.”  
She nods silently.  
“So… Toriel said you had an experiment to do? Involving my Determination?”  
“O—oh, yes! Well, based on what you’ve told me, I d—don’t need to do that anymore.”  
“What were you going to do?”  
“W—well, I made a machine that uses your D—Determination to… well… place yourself in the mind of others. It can even work b—backwards in time.”  
“Wow.” I reply. “That is… very powerful.”  
“Y—yeah. The catch is that the user has to have huge amounts of Determination. More than e—even the fallen humans before you. As such, th—there are very few people who can use it.”  
I raise my eyebrow. “Interesting.”  
“Yeah. B—but we don’t need to use it anyway.”  
“So,” I say, “anything else we need to do?”  
“W—well, I am curious about a certain aspect of what happened with Asriel.” She takes a deep breath, and begins telling me her idea.

“...to check out the soul containers.”  
“Check out the soul containers? You mean, go back to the Underground?”  
“Y—yeah. We won’t be going ourselves, of course! I’ll a—ask Sans to do it. Let’s call him now.”  
She takes her cell phone out and puts in a few numbers. It rings a couple times, then a low voice comes out of it.  
“yeah,” Sans yawns, evidently only just having woken up, “what is it, alphys?”  
“W—we need help with something. Could you come to the l—lab, please?”  
“sure. just a sec.”  
He walks into the room before Alphys can even hang up. “hey, guys. what do you need?”  
“W—well, we need you to go back to the Underground.”  
“why? the grillby’s there is closed.”  
“We n—need you to check the soul containers.”  
“ok... may i ask why?”  
“F—Frisk told me some things about how the b—barrier was destroyed. This is relevant to th—that.”  
“got it. what exactly am i looking for?”  
“Just t—tell us what you see.”  
“alright. see you guys.”  
He leaves.

“okay, so the souls are still in their containers… somehow.” Sans says through the phone.  
“A—ah, okay. That’s good!” Alphys replies. “While you’re at it, c—could you take a look at the coffins?”  
“ok, but… why?”  
“Why not?” I put in.  
I hear a chuckle. “fair enough. i can’t argue with that.”  
There is a rustling sound. “alright, i’m here. coffin number one, with the yellow soul, has a body in it. this is in strangely good condition for a corpse, but whatever, i guess.”  
“Um… M—move on to the next one,” Alphys says.  
“okay, so we have a green soul on the front of the second one. there is another body that’s clearly been very well-preserved. i honestly don’t know what you’re searching for here, alphys.”  
“W—well, I was wondering whether they could maybe have their s—souls restored to them.”  
“...ah, okay. well, this purple one is in great shape, and this dark blue one is doing pretty good too. next is… uh… the… the orange one. it… oh, god…” His voice sounds...strained, like he’s on the verge of tears. I never knew skeletons even could cry.  
“can... can i have a moment?”  
“O—okay…”  
“i’ll... i’ll call you back later.”  
He hangs up without waiting for a response.  
Alphys and I exchange a worried look.


	2. Chapter 2

“Goal!”  
The cheerful shout makes me look back up at the patch of grass in front of me. I’m leaning on a wooden fence, watching some kids play football. From what I can tell, the team on my left is winning— which is understandable, as the other team appear to have made the error of making Monster Kid the goalie; as he has no arms, he isn’t very good in the position.  
I'm trying to concentrate on the game in front of me, but I keep getting distracted thinking about yesterday. What happened to Sans? What will Alphys's experiment with the human souls involve? Because Sans didn't call back for ages, Alphys told me that I should head home and get some rest, as she would probably be needing me the next day. Before that, though, she gave me her number, so that she wouldn't have to send messages through Toriel anymore.  
I feel a tap on my shoulder.  
"FRISK?" Papyrus says.  
"Yeah?"  
"OH, I WAS JUST WONDERING IF YOU WERE OKAY! YOU SEEM KIND OF DOWN AT THE MOMENT!"  
"Oh, it's fine, I'm just… thinking about things."  
"WHAT ARE YOU THINKING ABOUT?"  
"Alphys is planning a project to attempt to replace the souls of the humans Asgore killed."  
"I SEE…"  
"I'm just not sure if it will work, and also… have you talked to your brother since yesterday?"  
"HMMM… I REMEMBER HEARING HIM COME HOME REALLY LATE AT NIGHT. I WAS IN BED, SO I COULDN'T TALK TO HIM. HE WENT STRAIGHT TO HIS ROOM."  
"Right…"  
"WHY ARE YOU ASKING?"  
"Alphys and I asked him to check out the soul containers and the coffins. When he got to the orange coffin, he seemed like he was… struggling with emotions."  
"I SEE… I'LL TALK TO HIM! I'M SURE I CAN CHEER HIM RIGHT UP!"  
"Yeah, you definitely can."  
"WELL, GOTTA GO!"  
Papyrus hurries away in the direction of his house. I smile a bit.  
"Yo, Frisk!"  
I glance back to the football game to see all the players looking at me. "Yo, wanna join in?" Monster Kid says.  
"I don't really like football…"  
"Come on, Frisk!" Another one of them says. "We can play something else!" She turns to the others. "Let's cheer Frisk up!"  
I smile. "Thanks, guys." I grab the fence and swing myself over. A chorus of cheers rings out from the group.

“Alright guys, I have to go now,” I say to everyone.  
“Bye, Frisk!” They call back.  
I go to the wooden gate and open it up. Closing it behind me, I walk over to the bench and sit down next to Sans.  
“You’ve been sitting there staring at me for like fifteen minutes. It’s gotten kind of creepy.”  
He shrugs. “well, i didn’t wanna interrupt since you looked like you were having fun, but i did wanna let you know i want to talk to you.”  
“And what is it you want to talk about?”  
“i’ll tell you at grillby’s. it’s starting to rain out here, and i’m hungry.”  
“Are we gonna use another one of your 'shortcuts'?"  
"of course."  
I stand up, but he gestures for me to sit back down.  
"don't bother getting up."  
I sit back down on the stool.  
"what are you ordering?" Sans asks.  
"I'll have a burger."  
"got it. hey, grillby, we'll have a burger for frisk and some fries for me. put it on my tab." Then he turns to me. "i bet you're wondering what happened to me yesterday."  
I nod.  
"well… remember how i said toriel made me promise to help any fallen humans? well… a couple of humans had already fallen down before then. and… remember that other thing i said?"  
"You said 'Y o u ' d b e d e a d w h e r e y o u s t a n d .'"  
"yeah. you, uh, you really didn't have to do the voice."  
"I thought it would be fun to do the voice."  
"right. so yeah, i— oh, here comes the food."  
Grillby puts our orders down onto the bar in front of us.  
"want any ketchup?" Sans asks, either deliberately avoiding or actually forgetting what we were talking about.  
"Sure."  
He hands over the bottle and I squirt some sauce inside my burger, then return the container to him.  
I don't really think there's anything else to discuss on this topic, so I change the subject whilst we eat.  
"Have you talked to Alphys yet?"  
"briefly. she said she'd text us when she was ready to start on her idea."  
"Do you think it will work?"  
"i don't know. but i trust her. she's pretty smart. sure, she's made mistakes, but we all have. i know i have. what about you, what do you thank about this plan of hers?"  
"I have my doubts about it, to say the least. Then again, it could be possible, since those souls aren't broken, so they may still be able to be returned to the bodies. Restoring life to them sounds pretty difficult, though."  
"that's a good point, i suppose."  
Sans finishes his fries, pushes the plate away from him, and stands up.  
"well, that was nice. see you around, frisk."  
"Bye, Sans," I reply.  
Just as he turns around to leave, the first few tones of the Dog Song play from his phone. A few seconds later, the first notes of Hopes and Dreams plays from mine.  
I check my cell phone. It's a text message from Alphys:

"Need you at the lab in 20 minutes. Starting the project."

I look back up at Sans, who's just seen the message too. He sits back down next to me and waits for me to finish my burger.  
"alright, we ready to go?" He asks once I'm done.  
"Yeah."  
"let's roll out."  
We stand and make our way to the exit. Sans opens the door, and we step through into the lab.


	3. Chapter 3

“Y—you two are early,” Alphys remarks.  
“yeah, we were eating at grillby’s when we got your text.”  
“Great! So we can s—start now.” She takes out a piece of paper with what looks like a list scribbled on it. “S—Sans, I need you to bring me the soul containers and the coffins.”  
“seriously? i’m not that strong, alphys.”  
“I—I know that. That’s why I a—asked Undyne to help!”  
"NGAHHHHHH!"  
We turn around and watch as Undyne leaps down from… somewhere and crashes down onto a machine with her spear, causing a loud boom to echo throughout the lab, and definitely breaking the electrical device. I think that's the one that uses Determination to mess with brains, I don't really remember.  
"that, uh, wasn't really necessary," Sans says to Undyne.  
"I don't care!" She replies, grinning.  
“R—right. Sans and Undyne, go and collect what I asked for, p—please. Frisk, wait here with me.”  
I take a seat near the machine Undyne broke. It’s emitting a weird noise. I guess she really messed it up.

[sans]:

undyne stumbles as i yeet us both to the soul containers. she grabs hold of one to steady herself, and it begins tipping over before i quickly stop it from falling.  
“Alright,” undyne says, “which one shall we start with?”  
“how about the yellow one?”  
“Got it.” she grabs it and holds it tightly to her chest. i snap my fingers, which is actually completely unnecessary, and we’re back at the lab. undyne trips over again. the container flies from her grasp, but frisk manages to catch it before it hits the floor.  
“nice catch,” i tell them.  
“Thanks,” they say, “this thing’s pretty heavy, huh?”  
frisk sets it down on the machine beside them.  
"B—be more careful next time," alphys says.  
"Yeah, yeah, yeah," undyne replies dismissively, "it's fine, babe. Let's go get the rest!"  
we spend the next twenty or so minutes going back and forth between the lab for both the soul containers and the coffins— even undyne struggles to lift the coffins. we put the five souls lined up next to the one frisk put down, and the coffins go in the centre of the room. at last i sit down, exhausted. undyne stays standing, because of course she does.  
"So, what sciencey stuff are you gonna do?" undyne says.  
"W—well, it's kind of a trial and error thing. I j—just need to try a lot of methods, and s—see what works."  
"What methods are you gonna try?" she says, walking over to alphys.  
"W—well, first I'm gonna try extracting Determination from the souls and trying to inject it i—into them to revive them."  
undyne blinks a few times. "Yeah, babe, I don't know what that means. Doesn't matter, though." suddenly, she picks her up, provoking a little squeak. "It's late," undyne says. "You should rest, and work tomorrow." without waiting for an answer, she carries alphys, who kind of accepts this and rests against her, away.  
“that, uh, happened," i remark.  
frisk checks their watch. "It's ten thirty. I better be getting back home. Toriel could be worried."  
"see ya."

[Frisk]:

"Oh there you are, Frisk!" Toriel says as I enter the house. "I was getting worried."  
"Sorry, Tori. Alphys needed help at the lab."  
"I see. How's her little project going?"  
I haven't told Toriel what Alphys is doing, she just knows that Alphys is working on some kind of project.  
"She's ready to start. Sans, Undyne, and I helped to get everything ready for her."  
"Well, that's good. It's getting late, though. You should head to bed."  
I comply, since I'm pretty sleepy. I walk up the stairs, enter my room, and flop down onto my bed, barely managing to get myself into a comfortable position before I fall asleep. It's been a long day.

[Asgore]:

"Oh? What's this?" I say, surprised. Normally, I don't get anything in my mail, but today, it looks like someone's sent me a letter. That's… incredible, for a start. I take the envelope out. It's a plain sky blue, and says "To Asgore" on it.  
I open it up. Inside is a short message:

"Please come to the lab as soon as possible; I have something important I need to discuss with you.

Yours Sincerely,  
Alphys

P.S. Please get a cell phone, I hate writing letters"

Ooh, this sounds interesting. And she's right, I should probably get a phone. I haven't really needed one, since nobody talks to me… at all, really. It's lonely in my house, but my flowers keep me company. That's all I need.  
I close my mailbox and try to remember where the lab is. Okay, so… oh, I'll find it eventually. I'll just go.

I knock at the door. It took me… an embarrassingly long amount of time to find this place.  
The door slides open after a few moments, revealing Alphys standing there, with Undyne a few feet behind.  
"Hello you two," I say, "what can I do for you?"

[Frisk]:

"Ow!" I exclaim quietly, as I roll off of my bed and fall onto the floor. "That hurt."  
I get up into a sitting position on my bed, then stand with a bit more effort. My alarm clock is telling me that it's half past midnight.  
I tiptoe from my bed to the door of my room, which I attempt to open as quietly as possible. It creaks a little, but it should be fine.  
I leave the door ajar and make my way, very slowly, down the stairs and into the kitchen. There, I wash up a bowl and pour cereal and milk into it, which I eat speedily. Then I clean up and go back upstairs, once again trying to be silent. Toriel hates it when I wake her up whilst I'm getting some food or a drink late at night.  
I creep back into my room and close the door behind me. Then I whip around as I hear a voice.  
"hey, frisk."


	4. Chapter 4

"You scared me!" I exclaim loudly, relieved when I realise that it's Sans.  
"sorry. i couldn't really think of a good way to say hey."  
"What is it you want?"  
"well, i realised i never really explained myself in regards to the body with the orange soul. let's go to the lab."  
"Oh, uh, okay. Let me just write a note to Tori."  
"sure."  
I grab a pencil and scribble something down. Then I stick it to the front of my bedroom door and turn back to Sans. "Ready when you are."  
He gestures to the exit. "after you."  
I step through into the main room of the lab. It’s dark, and kind of creepy, but there’s just enough light to see by. I turn my head towards where I can hear voices from down the hall.  
“don’t worry,” Sans says. “we won’t be here for long.” He finds the coffin with the orange soul.  
“I kind of already figured it out,” I say.  
“yeah, but you don’t know the full story. this is what i’m about to tell you.”

[Toriel]:

I step out of my room and immediately go to check on Frisk. I heard a loud voice from their bedroom, so I wanted to see if everything is alright. As I approach, I spot a note on the front of their door:

“At the lab with Sans. Back soon.

—Frisk”

I sigh. Of course they are. I should really go check on those two.  
After hurriedly changing out of my pyjamas and into regular clothes, I step out of my house into the street. There's a voice behind me as I turn to the direction of the lab.  
"HEY, TORIEL!"  
Papyrus jogs up next to me.  
"Hi, Papyrus. Why are you out so late?"  
"MY BROTHER DECIDED IT WOULD BE A GOOD IDEA TO HEAD TO THE LAB AT THIS TIME OF NIGHT! WHAT ABOUT YOU?"  
"Sans brought Frisk with him, so I was going to the lab to check on them." I know Frisk can handle themselves, but it never hurts to go and see.  
"OF COURSE HE DID. WELL, LET'S GET THERE AS QUICK AS POSSIBLE!"  
We walk down the various twisting paths leading to the lab. We arrive, and check the door. It's locked, because that would be too easy.  
"HMM…" Papyrus says. "THERE MIGHT BE A WAY IN AT THE SIDE!"  
We check around the building. There are no side doors, but what we do find is a smashed window at our height.  
"THIS PLACE SMELLS KIND OF FISHY! MAYBE UNDYNE WAS HERE AND SMASHED THE WINDOW!"  
"But… why?"  
"BECAUSE UNDYNE!"  
"Fair enough. Let's go through."  
We help each other up into the hole. It leads through into a dark room. I can't see anything at all, so I feel around for a light switch and flick it on.  
It illuminates a small room with a large bed. Its sheets are messed up, like someone got out in a hurry. This place must be Alphys's; I can tell from the massive Mew Mew Kissy Cutie poster on the wall, alongside several figurines. She also appears to have written "Mew Mew 2" on a piece of paper and thrown it in the bin. Classic.  
We walk through and out of the exit, then up a flight of stairs. It finds us in a balcony looking over the main room of the lab. There's very little light other than that from the machines below. I can hear Sans's voice. Papyrus and I walk to the fence and look down, careful not to make any noise. Sans is standing next to a coffin, giving some sort of speech to Frisk. Well, at least those two aren't getting into any trouble yet.

[Asgore]:

"Oh, so is that all you need me to do?" I say.  
"Y—yeah," Alphys says.  
"Well, first I— oh, I feel terribly awkward just standing here, without like a cup of tea or anything."  
"We can get you something to drink," Undyne offers, "and a good place to sit while we talk."  
I nod. Alphys leads us around the lab   
and into a kitchen. There, Undyne brews us some tea while I take a seat at the table.  
"So, the first soul… I can't remember fully. I believe a monster in the ruins killed the first human. The next— oh, thank you." Undyne just brought the tea to the table and sat down beside Alphys.  
"Well, the next one…"

[PAPYRUS]:

WHAT ARE THOSE TWO EVEN DOING DOWN THERE? IT'S MIDNIGHT, WHY WOULD SANS NEED TO TALK TO FRISK THIS URGENTLY?  
"We should go down there," TORIEL SAYS.  
I NOD, BUT I DON'T REPLY SINCE I'M NOT GOOD AT CONTROLLING THE VOLUME OF MY VOICE.  
I FOLLOW TORIEL AS SHE WALKS TO THE END OF THE HALLWAY. THERE'S A WOODEN STAIRCASE THERE, WHICH WE QUIETLY MAKE OUR WAY DOWN. AT THE BOTTOM, THE CORRIDOR SPLITS OFF INTO TWO DIRECTIONS. TORIEL TURNS TO ME, UNSURE WHICH WAY TO GO. I POINT TO THE LEFT, ENTIRELY OUT OF RANDOM SELECTION. SHE NODS, AND WE PROCEED IN THAT DIRECTION.

[sans]:

"...and that's basically it."  
"I see…" frisk replies. "So in a way, we kind of have you to thank for being on the surface?"  
i shrug. "if it hadn't been me, it would have been someone else."  
“I suppose so. Is that all you need to talk about, then?”  
“i think so. i guess i’d best be— hold up. why is that soul glowing?”  
frisk follows the index finger that I point towards what i’m talking about. atop one of alphys’s machines, the first soul that undyne and i retrieved is glowing.  
frisk steps forward. “Huh,” they say. “That’s weird. I wonder if—”  
all of a sudden, the machine appears to turn on, accompanied by several loud groaning noises. frisk takes a step back. then they try to take another one…  
and they can’t.  
“What the… something’s blocking me!”  
their body looks like it’s gradually getting brighter and brighter. i run forward to help them, but that barrier seems to be restraining me, as well. i can only watch as frisk becomes lighter and lighter, until—

[Asgore]:

“..was killed somewhere in Waterfall, I think.”  
Alphys nods. “So, is that—”  
She is cut short by the sound of a voice shouting, echoing throughout the lab.  
“FRISK!”  
Undyne jumps to her feet. “What the heck was that?”  
“I—I don’t know,” Alphys replies, “but it doesn’t sound good.”  
We leave and rush through the building, trying to find the source of the yell. Soon, we find ourselves at the entrance of the main room. We walk in.  
As we enter, another group of people runs in from the opposite exit: Toriel and Papyrus. This confuses me even more.  
Both parties shift their gaze to the side of the room. Sans is sitting on the floor, looking at one of Alphys’s machines. He seems to be in… shock?  
After a few seconds, he turns around to talk to both of the groups in the room.  
“guys,” he says, “we may have a problem.”

**Notes for the Chapter:**

> and so, the four-thousand-plus word prologue finally ends

**Author's Note:**

> This is my first work and I'm scared


End file.
